<template>
  <div>
    <div :style="{ marginLeft: '500px' }">
      <p>请选择你要购买的书籍</p>
      <ul>
        <li v-for="(item, i) in arr" :key="i">
          <span>{{ item.name }}</span>
          <button @click="addFn(i)">买书</button>
        </li>
      </ul>
      <table border="1" width="500" cellspacing="0">
        <tr>
          <th>序号</th>
          <th>书名</th>
          <th>单价</th>
          <th>数量</th>
          <th>合计</th>
        </tr>
        <tr v-for="(item, i) in arr" :key="i">
          <td>{{ i + 1 }}</td>
          <td>{{ item.name }}</td>
          <td>{{ item.price }}</td>
          <td>{{ item.count }}</td>
          <td>{{ item.price * item.count }}</td>
        </tr>
      </table>
      <p>总价格为:{{ total }}</p>
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },

  // 点击买书，该行的书的count就增加
  methods: {
    addFn(index) {
      this.arr[index]["count"]++;
    },
  },

  computed: {
    total() {
      return this.arr.reduce((prve, item) => {
        return (prve += item.price * item.count);
      }, 0);
    },
  },
};
</script>
